It has been demonstrated that nanowire grid polarizers comprising a metal grating, traditionally fabricated on glass substrates, can also be fabricated on plastic films. Compared to glass, plastic is cheap, allows fabrication over a large area with high throughput and finds use in applications which need to be lightweight and flexible (e.g. printed electronics, wearable electronics).
For example, the publications “Large flexible nanowire grid visible polarizer made by nanoimprint lithography” (by Chen, L., Wang, J. J., Walters, F., Deng, X. G., Buonanno, M., Tai, S. & Liu, X. M. (2007) Applied Physics Letters, 90) and “Direct imprinting on a polycarbonate substrate with a compressed air press for polarizer applications” (by Lin, C. H., Lin, H. H., Chen, W. Y. & Cheng, T. C. (2011), Microelectronic Engineering, 88, 2026-2029) disclose optical element structures that have non-flat spectral response of light over a visible wavelength range. This non-flat spectral response results in an undesirable reddish artifact for plastic nanowire grid polarizer operating in transmission mode. A further discussion on the operating principle of a nanowire grid polarizer is described further below, with reference to FIG. 10A.
A need therefore exists to provide an optical element and its method of fabrication that can address the undesirable attributes, such as the associated reddish artifact, of optical element structure fabricated from existing plastic nanowire grid polarizers.